Method for recovering and separating unsaturated fluorinated hydrocarbons

Abstract

A process for recovering and upgrading unsaturated fluorinated hydrocarbons, comprises: a) providing a foam M1 consisting of pores containing a composition C1 comprising at least one unsaturated fluorinated hydrocarbon; b1) optionally grinding or compressing said foam M1 to form a ground foam or a compressed foam; b2) optionally recovering at least a portion of said composition C1; c) depolymerizing or dissolving said foam M1 provided in step a) or said ground or compressed foam obtained in step b1); d) recovering at least a portion of said composition C1 and optionally mixing the latter with said at least a portion of the composition recovered in step b2) to form a stream A comprising at least one unsaturated fluorinated hydrocarbon; e) recovering and separating said stream A into a plurality of streams of which at least one stream B1 comprises said at least one unsaturated fluorinated hydrocarbon.

The invention claimed is: 
     
       1. A process for recovering and upgrading unsaturated fluorinated hydrocarbons, comprising the steps of:
 a) providing a foam M1 consisting of pores containing a composition C1 comprising at least one unsaturated fluorinated hydrocarbon; 
 b1) optionally grinding or compressing said foam M1 provided in step a) to form a ground foam or a compressed foam; 
 b2) optionally recovering at least a portion of said composition C1 released during step b1), wherein released composition C1 is in a gaseous phase; 
 c) depolymerizing or dissolving said foam M1 provided in step a) or said ground or compressed foam obtained in step b1); 
 d) recovering at least a portion of said composition C1 released during step c), wherein released composition C1 is in a gaseous phase, and optionally mixing it with said at least a portion of the composition C1 recovered in step b2) to form a stream A comprising at least one unsaturated fluorinated hydrocarbon; and 
 e) recovering and separating said stream A formed in step d) into a plurality of streams of which at least one stream B1 comprises said at least one unsaturated fluorinated hydrocarbon. 
 
     
     
       2. The process as claimed in  claim 1 , wherein the unsaturated fluorinated hydrocarbon comprises three or four carbon atoms. 
     
     
       3. The process as claimed in  claim 1 , wherein said unsaturated fluorinated hydrocarbon contains a single carbon-carbon double bond. 
     
     
       4. The process as claimed in  claim 1 , wherein said foam M1 consists of a polymer selected from the group consisting of polyurethane, polyolefin, poly(methyl methacrylate), polyhydroxyalkanoate, polylactic acid, polyimide, poly(vinyl chloride), poly(ethylene/vinyl acetate), poly(etherimide), poly(methacrylimide), polycarbonate, polystyrene, and a mixture thereof. 
     
     
       5. The process as claimed in  claim 1 , wherein said foam M1 provided in step a) consists of polystyrene; and step c) is carried out in the presence of an organic solvent capable of dissolving the polystyrene or step c) is carried out by thermal depolymerization of the polystyrene. 
     
     
       6. The process as claimed in  claim 1 , wherein said foam M1 provided in step a) consists of polyurethane and step c) is carried out by an alcoholysis or hydrolysis or ammonolysis or aminolysis reaction. 
     
     
       7. The process as claimed in  claim 1 , wherein step c) results in the formation of polyol compounds, the latter being recovered, purified and recycled into a process for the production of polyurethane. 
     
     
       8. The process as claimed in  claim 1 , wherein step e) of separating said stream is carried out by distillation, azeotropic distillation, pressurized distillation, extractive distillation, cold separation, absorption in a solvent, or a combination thereof. 
     
     
       9. The process as claimed in  claim 1 , wherein said stream A is subjected to a step of adsorption prior to step e) or said stream B1 is subjected to a step of adsorption after step e). 
     
     
       10. The process as claimed in  claim 1 , wherein said at least one unsaturated fluorinated hydrocarbon included in said composition C1 is selected from the group consisting of 3,3,3-trifluoropropene, 2,3,3,3-tetrafluoropropene, (E/Z)-1,3,3,3-tetrafluoropropene, (E/Z)-1,2,3,3,3-pentafluoropropene, 2-chloro-3,3,3-trifluoropropene, 1-chloro-3,3,3-trifluoropropene, 1,1-dichloro-3,3,3-trifluoropropene and 1,2-dichloro-3,3,3-trifluoropropene, (E/Z)-1,1,1,4,4,4-hexafluorobut-2-ene, 2,4,4,4-tetrafluorobut-l-ene, and mixtures thereof. 
     
     
       11. The process as claimed in  claim 10 , wherein said composition C1 also comprises a hydrofluorocarbon other than said at least one unsaturated fluorinated hydrocarbon, an alkane, methyl formate, an inert gas, an alcohol, an ether, a fluorinated ether, an unsaturated fluorinated ether, a ketone, a fluoroketone, a chlorofluorocarbon or water, or a mixture thereof. 
     
     
       12. The process as claimed in  claim 11 , wherein said hydrofluorocarbon other than said at least one unsaturated fluorinated hydrocarbon is selected from the group consisting of difluoromethane (HFC-32), fluoroethane (HFC-161), 1,2-difluoroethane (HFC-152), 1,1-difluoroethane (HFC-152a), 1,1,2-trifluoroethane (HFC-143), 1,1,1-trifluoroethane (HFC-143 a), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1,2,2-pentafluoroethane (HFC-125), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,2,3,3,3-hexafluoropropane (HFC-236ea), 1,1,1,3,3-pentafluorobutane (HFC-365mfc), and 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea). 
     
     
       13. The process as claimed in  claim 11 , wherein said chlorofluorocarbon is selected from the group consisting of trichlorofluoromethane, dichlorodifluoromethane, trichlorotrifluoroethane, dichlorotetrafluoroethane and chloropentafluoroethane. 
     
     
       14. The process as claimed in  claim 1 , wherein said stream A comprises a content of said at least one fluorinated hydrocarbon of between 50% and 99% by volume, based on the total volume of said stream A. 
     
     
       15. The process as claimed in  claim 1 , wherein step a) also comprises:
 providing a foam M2 consisting of pores containing a composition C2 comprising a hydrofluorocarbon selected from the group consisting of difluoromethane (HFC-32), fluoroethane (HFC-161), 1,2-difluoroethane (HFC-152), 1,1-difluoroethane (HFC-152a), 1,1,2-trifluoroethane (HFC-143), 1,1,1-trifluoroethane (HFC-143a), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1,2,2-pentafluoroethane (HFC-125), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,2,3,3,3-hexafluoropropane (HFC-236ea), 1,1,1,3,3-pentafluorobutane (HFC-365mfc), and 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), or 
 providing a foam M3 consisting of pores containing a composition C3 comprising a chlorofluorocarbon selected from the group consisting of trichlorofluoromethane, dichlorodifluoromethane, trichlorotrifluoroethane, and dichlorotetrafluoroethane, chloropentafluoroethane, or 
 providing a mixture of said foams M2 and M3. 
 
     
     
       16. The process as claimed in  claim 15 , wherein the foam M2 and the foam M3 consist of a polymer identical to that of said foam M1. 
     
     
       17. The process as claimed in  claim 15 , wherein the composition C2 and the composition C3 are devoid of unsaturated fluorinated hydrocarbon. 
     
     
       18. The process as claimed in  claim 15 , wherein it comprises the steps of:
 b1) optionally grinding or compressing said foam M1, said foam M2 and/or said foam M3 provided in step a) to form a ground foam or a compressed foam; 
 b2) optionally recovering at least a portion of said composition C1 and at least a portion of said composition C2 and/or at least a portion of said composition C3, released during step b1); 
 c) depolymerizing or dissolving said foam M1 and said foam M2 and/or said foam M3 provided in step a) or said ground or compressed foam obtained in step b1); 
 d) recovering at least a portion of said composition C1 and at least a portion of said composition C2 and/or at least a portion of said composition C3, released during step c), and optionally mixing them with those recovered in step b2) to form a stream A; 
 e) recovering and separating said stream A into a plurality of streams of which at least one stream B1 comprises said at least one unsaturated fluorinated hydrocarbon. 
 
     
     
       19. The process as claimed in  claim 18 , wherein said stream A comprises a content of said at least one fluorinated hydrocarbon of between 0.1% and 50% by volume, based on the total volume of said stream A.